Medical endoscopes are used to inspect regions within the body, such as cavities, organs, and joints. Endoscopes typically include a rigid or flexible elongated insertion tube having a set of optical fibers that extend from a proximal handle through the insertion tube to the distal viewing tip of the endoscope. Alternatively, an image sensor, such as a CCD, is positioned near the distal viewing tip. An external or internal light source provides light to the area of interest in the body in the vicinity of the distal tip.
U.S. Pat. No. 5,710,661 to Cook, which is incorporated herein by reference, describes optical apparatus that monitors an entire panorama in low resolution and simultaneously monitors a selected portion of the panorama in high resolution. A mirror having a convex surface of revolution with a hole therein is used as the panoramic portion of the apparatus. The higher resolution part of the apparatus uses a pointing mirror positioned above this hole. The panoramic and higher resolution views are imaged through lenses or optical components onto a detector. The panoramic view is imaged onto the detector as an annulus of light in which either higher or lower elevational angles of the panorama are imaged further away from the detector's center depending upon how the convex mirror is configured. In this way, the resolution of that portion of panorama that is imaged further away from the detector's center is enhanced. The higher resolution view is imaged to the center of the annulus.
U.S. Pat. No. 6,341,044 to Driscoll, Jr. et al., which is incorporated herein by reference, describes a panoramic imaging arrangement comprising a lens block and a system of lenses. The lens block has a substantially vertical axis of revolution and is capable of receiving light from a first, 360 degree surrounding panoramic scene. The system of lenses has a vertical axis of revolution substantially coinciding with the axis of revolution of the lens block, and is positioned to receive light from a second scene which is at least partially located above the first, surrounding panoramic scene.
U.S. Pat. No. 6,493,032 and US Patent Application Publication 2002/0012059 to Wallerstein et al., which are incorporated herein by reference, describe a method for viewing an image. Light projected from the image is split into first and second bundles of light focusing over a first and a second focal region, respectively. The light at the first focal region is detected at a first resolution. The light at the second focal region is detected at a second resolution different from the first resolution.
U.S. Pat. No. 6,356,296 to Driscoll, Jr. et al., which is incorporated herein by reference, describes a panoptic camera system that can be used to capture all the light from a hemisphere viewing angle. The panoptic camera comprises a main reflecting mirror that reflects light from an entire hemisphere onto an image capture mechanism. The main reflecting mirror consists of a paraboloid shape with a dimple on an apex. The surface area around the dimple allows the main reflector to capture light from behind an image capture mechanism or a second reflector.
U.S. Pat. Nos. 6,459,451 and 6,424,377 to Driscoll, Jr. et al., which are incorporated herein by reference, describe a panoramic camera apparatus that captures a 360 degree panoramic image. The panoramic image is recorded as a two dimensional annular image. Techniques are described for digitally performing a geometric transformation of the two dimensional annular image into rectangular projections such that the panoramic image can be displayed using conventional methods.
U.S. Pat. No. 6,373,642 to Wallerstein et al., which is incorporated herein by reference, describes a panoramic imaging arrangement that includes a first lens block including a convex reflective surface and a transparent component. The convex reflective surface has a substantially vertically extending axis of revolution and is capable of receiving light from a 360 degree surrounding panoramic scene, and reflecting the light for further manipulation. The transparent component covers the convex reflective surface, so as to protect the convex reflective surface from environmental conditions.
U.S. Pat. No. 6,388,820 to Wallerstein et al., which is incorporated herein by reference, describes a panoramic imaging arrangement that includes at least a first lens block including a convex reflective surface and a transparent component. The convex reflective surface has a substantially vertically extending axis of revolution which is described as being capable of receiving light from a 360 degree surrounding panoramic scene, and reflecting the light for further manipulation. The transparent component covers the convex reflective surface. The convex reflective surface is thereby protected from environmental conditions which may otherwise result in damage to the convex reflective surface.
U.S. Pat. No. 6,597,520 to Wallerstein et al., which is incorporated herein by reference, describes a panoramic imaging arrangement comprising a first and second transparent component both rotationally symmetric about an axis of revolution. The first transparent component has an upper surface and a lower surface. The lower surface includes a reflective portion and a refractive portion both about the axis of revolution. The refractive portion extends radially from the axis of revolution to the start of the reflective portion. The second transparent component is attached to the first transparent component at a refractive interface that extends into the upper surface. The second transparent component includes a distal reflective surface. Light from a portion of a surrounding panoramic scene is refracted by a portion of the upper surface, and is reflected by the reflective portion of the lower surface through the refractive interface to the distal reflective surface. Once reflected from the distal reflective surface, the light again passes through the refractive interface and exits the first transparent component through the refractive portion of the lower surface.
U.S. Pat. No. 4,647,761 to Cojan et al., which is incorporated herein by reference, describes an airborne system for the electro-optical detection, location and omnidirectional tracking of a target. The system has an input objective lens carried by a universal joint, whereof one frame is rotated circularly in azimuth and the second frame moves the optic in elevation. An image offsetting optical section integral with the universal joint maintains the image centering through the detection plane, the detector being fixed. The image offsetting optical section is catadioptric and has an input mirror integral with the objective lens, and an output mirror integral with the first frame and which reflects the radiation along the circular rotation axis. The input objective lens focuses the radiation in an image plane located on the optical path between two mirrors, and a second optical objective lens re-forms the field image in the detection plane.
U.S. Pat. No. 5,790,182 to St. Hilaire, which is incorporated herein by reference, describes techniques for wide-angle imaging to create a high resolution image using a convex primary mirror concentrically positioned relative to a concave secondary mirror and one or more detectors spherically juxtaposed. The radii of the primary and secondary mirrors are related by the square of the “golden ratio” to reduce low order aberrations. A fiber optic faceplate coupled to each detector corrects field curvature of the image which may then be detected with a conventional flat detector.
U.S. Pat. No. 6,130,783 to Yagi et al., which is incorporated herein by reference, describes an omnidirectional panoramic visual sensor including a convex mirror with a surface of revolution having a focal point, a plurality of mirrors with surfaces of revolutions having at least one focal point, a photoreceiving lens system receiving light reflected by the convex mirror with the surface of revolution and the plurality of mirrors with surfaces of revolutions, and an image acquisition surface. The convex mirror and the plurality of mirrors are so arranged that the focal point of a first mirror included in the convex mirror and the plurality of mirrors aligns with the focal point of a second mirror, included in the convex mirror and the plurality of mirrors, further reflecting light reflected by the first mirror.
U.S. Pat. No. 6,646,818 to Doi, which is incorporated herein by reference, describes a panoramic imaging lens having an annular light incident surface formed in a substantial convex lens form; a first reflective surface formed in an annular concave mirror form to reflect light inside the lens; a second reflective surface provided at a central part inside the annular light incident surface to reflect the reflected light from the first reflective surface toward an inner part of the annular first reflective surface; and a light outgoing surface positioned at a central part inside the annular first reflective surface and opposing the second reflective surface to transmit light. A non-reflective part exerting no regular reflection of light is provided on a light path toward the light incident surface amongst light paths of light proceeding to agree with a light path of imaging light incident on and refracted at the light incident surface and proceeding inside the lens.
U.S. Pat. No. 6,222,683 to Hoogland et al., which is incorporated herein by reference, describes a panoramic imaging arrangement comprising a transparent component and a reflective material. The transparent component has a first surface about a vertical axis of revolution, a second surface about the axis of revolution, and an opening formed therein to define a third, internal surface about the axis of revolution. The third surface has a concave profile in a plane of the axis of revolution. The reflective material is located on the second surface to provide a reflective surface against the second surface. The first surface, the reflective surface, and the third surface are positioned relative to one another so that light from a 360 degree surrounding panoramic scene enters the transparent component through the first surface, is reflected from the reflective surface, and exits the transparent component through the third surface.
U.S. Pat. No. 6,304,285 to Geng, which is incorporated herein by reference, describes an omnidirectional imaging system comprising a reflective mirror for viewing object within a hemispherical field of view form a single virtual view point at the local center of said reflective mirror, a projector for projecting a light beam toward said reflective mirror, and a variable wavelength filter optically positioned between said projector and said reflective mirror for generating a pattern having a spatially distributed wavelength spectrum of said reflective mirror.
U.S. Pat. No. 5,473,474 to Powell, which is incorporated herein by reference, describes a panoramic imaging system for projecting a 360 degree cylindrical field of view onto a two-dimensional annular format. The system has a panoramic imaging block with a concentric axis of symmetry, two refractive surfaces and two reflective surfaces. The first reflective surface is a concave conicoid of revolution with the conic constant in the range of −0.6 to +2.0. In an embodiment of the invention, the second refractive surface (the last in the path of rays) is flat, while the first reflective surface, the second reflective surface, and the first refractive surface are all spherical.
U.S. Pat. No. 5,920,376 to Bruckstein et al., which is incorporated herein by reference, describes an omnidirectional or panoramic viewer/projector that uses a single camera and a mirror with a curved surface. The curved mirror provides a single virtual optical center or viewpoint.
U.S. Pat. No. 6,375,366 to Kato et al., which is incorporated herein by reference, describes an omnidirectional camera device that is able to restrict a range in which images of objects are detected. This omnidirectional camera device comprises a rotationally-symmetric convex mirror fixedly attached to one end of a transparent tube assembly, an image pickup means disposed on the other end of the tube assembly in an opposing relation to this convex mirror, and a cover assembly disposed on the tube assembly for restricting the range in which light becomes incident on the convex mirror. The cover assembly is mounted on one end side of the tube assembly, and is attached to the tube assembly so as to become freely rotatable.
U.S. Pat. No. 5,739,852 to Richardson et al., which is incorporated herein by reference, describes an electronic imaging system for capturing an image comprising a lens and an imaging sensor. The imaging sensor includes a plurality of imaging elements, the plurality of imaging elements having a distribution on the surface representable by a nonlinear function. The distribution of imaging elements has a relatively low density at a center point of the surface and a relatively high density at a point along a periphery of the surface.
U.S. Pat. No. 6,115,193 to Shu, which is incorporated herein by reference, describes a device for creating a panoramic field of view, comprising a first light-passing incident surface which is a cylinder surface and a second incident surface which is a mirror surface onto which light passing through the first surface impinges. A third incident surface onto which light from the second incident surface impinges is aspherical. A recollimating element for presenting a pupil plane depiction of a panoramic field of view is also provided.
U.S. Pat. No. 5,502,592 to Jamieson, which is incorporated herein by reference, describes a wide-aperture infrared lenses with hyper-hemispherical fields of view (e.g., up to 270 degree) and at wide relative apertures (e.g., up to f/0.7) to produce images having low distortion—typically no more than 20% greater than the distortion resulting when the image size is proportional to the field angle.
U.S. Pat. No. 4,012,126 to Rosendahl et al., which is incorporated herein by reference, describes an optical system for 360 degree image transfer in which spaced primary and secondary hyperbolically surfaced mirrors are combined with a refractive lens system and are held in spaced relation by a transparent envelope having inner and outer surfaces generated from the near focal point of the primary mirror to avoid ray pass through distortion, and in which the mirrors are so spaced and concentrically arranged that the entrance pupil of the lens system coincides with the near focal point of the primary mirror, which is centrally apertured to form an aperture stop (diaphragm), and the near focal point of the secondary mirror approximates the apex of the primary mirror, the far focal points of the mirrors coinciding to form a confocal set of mirrors.
U.S. Pat. No. 6,028,719 to Beckstead et al., which is incorporated herein by reference, describes an imaging system that comprises a panoramic imaging element. The panoramic imaging element is described as being capable of imaging a full 360 degree panoramic image and a forward image onto a single plane.
U.S. Pat. No. 6,704,148 to Kumata, which is incorporated herein by reference, describes an omnidirectional imaging device including a retainer having a top section, a body section, and a bottom section. A mirror having a surface of revolution is mounted on the top portion of the body section. The bottom section is assembled with a mounting base for movably mounting an image pickup device, and with a fixture for fixing the image pickup device to the mounting base.
U.S. Pat. No. 4,976,524 to Chiba, which is incorporated herein by reference, describes an optical system for endoscopes including at least one convex or concave aspheric surface, and a reflecting mirror arranged on the front side of the imaging optical system and having a reflecting surface shaped like a spherical or aspheric surface.
U.S. Pat. No. 6,611,282 to Trubko et al., which is incorporated herein by reference, describes a system for capturing super wide-angle panoramic images. In particular, a two-reflector system is described which is substantially self-correcting in which optical aberrations are substantially eliminated, such as field curvature, astigmatism and the like. In an embodiment of the invention, two reflectors (e.g., one a hyperboloidal mirror, the other a concave ellipsoidal or spherical mirror), a relay system (e.g., optics such as a mirror, a lens, or a pinhole), and an image sensor are provided.
U.S. Pat. No. 6,333,826 to Charles, which is incorporated herein by reference, describes an omniramic wide angle optical system comprising a Cassegrain system having a strongly curved convex reflecting surface with a prolate aspheric figure, a secondary reflector surface, and a modular imaging and correcting lens system. Also described is the conversion of a two dimensional annular image or a segment thereof to a viewable horizontal image or a subset thereof, or from a horizontal format image or a subset thereof into an annular image or a segment thereof.
U.S. Pat. No. 6,449,103 to Charles, which is incorporated herein by reference, describes an omnidirectional wide angle optical system comprising an external refracting surface which may be strongly curved, a strongly curved internal primary reflector surface, a secondary reflector surface, central wide angle refracting optics, a modular or integral imaging and correcting lens system which may have aperture adjustment means, and mounting components. Optical surfaces associated with the formation of an omidirectional virtual image are typically integrated into a single solid catadioptric optic in some embodiments, but central or peripheral wide angle refracting optics which may provide supplemental coverage are separate optical elements in other embodiments.
U.S. Pat. No. 6,157,018 to Ishiguro et al., which is incorporated herein by reference, describes an omidirectional vision sensor that comprises a rotationally symmetrical convex mirror and a camera arranged opposite the mirror. The rays of light which internally reflect inside the cylinder pass through the production line of the rotational axis of the convex mirror, and are thus eliminated before they reach the inner surface of the transparent cylinder. A tapered object on the vertex of the convex mirror is described as completely eliminating inner reflected rays of light.
US Patent Application Publication 2002/0109773 to Kuriyama et al., which is incorporated herein by reference, describes an imaging device that includes a convex mirror for reflecting first incident light representing an object, the convex mirror having a shape of a solid of revolution; an imaging mechanism for capturing a reflected image represented by light reflected in the convex mirror; and an optical member for guiding the first incident light toward the convex mirror and guiding the reflected light toward the imaging mechanism. The optical member has an attenuation section for attenuating second incident light which (a) is incident on an outer circumferential surface of the optical member in a direction opposite the first incident light, (b) passes through the optical member, (c) is reflected by an inner circumferential surface of the optical member so as to be directed toward the convex rotational mirror, and (d) is superimposed on the first incident light.
US Patent Application Publication 2002/0109772 to Kuriyama et al., which is incorporated herein by reference, describes an imaging device including a convex mirror for reflecting incident light representing an object, the convex mirror having a shape of solid of revolution; an imaging mechanism for taking an image represented by reflected light from the convex mirror; and an optical member for guiding the incident light toward the convex mirror and guiding the reflected light toward the imaging mechanism, the optical member being in close contact with the convex mirror.
US Patent Application 2004/0004836 to Dubuc, which is incorporated herein by reference, describes an internal reflection element having a plurality of internal reflection faces and a plurality of exit faces which redirect light from a light source into a side direction. The curved entry faces have the optical effect of concentrating incident light onto a center of the corresponding internal reflection face. This is described as allowing light impinging on the internal reflection face from a wide range of angles to be redirected for side projection through the desired exit face.
US Patent Application Publication 2004/0249247 to Iddan, which is incorporated herein by reference, describes an endoscope capable of capturing images of an in-vivo area behind a distal end of the endoscope's tube. The endoscope has an imaging unit that includes a reflective surface that reflects an image of an area surrounding such tube onto an image sensor.
US Patent Application Publication 2003/0191369 to Arai et al., which is incorporated herein by reference, describes an omnidirectional endoscope device at a distal end part of an insertion section of an endoscope with an omnidirectional light receiving unit for receiving incident light from all around the periphery in the peripheral direction and reflecting the light toward a relay lens optical system. The insertion section slidably pierces a retaining cylinder. A light guide is embedded in the retaining cylinder, and an outgoing surface at the distal end of the light guide is faced with a distal end face of the retaining cylinder. The retaining cylinder can be operated in a sliding manner by a grip disposed at the basal end. The light thereby strikes the view field of the omnidirectional light receiving mechanism regardless of whether the inside space of an image to be observed is large or small.
PCT Publication WO 01/68540 to Friend, which is incorporated herein by reference, describes an imaging apparatus comprising two imaging units for producing images of respective scenes, each imaging unit comprising optical means for gathering light over a wide sector and directing it to image sensing means. The optical means of the imaging units can be back-to-back so as to encompass the imaging sensing means and each unit can include a convex reflector for reflecting light from a panoramic scene onto a planar reflector which reflects light through a port or ports in the convex reflector onto a CCD array within the convex reflector.
PCT Publication WO 02/059676 to Gal et al., which is incorporated herein by reference, describes a spherical view imaging apparatus comprising an axisymmetric form comprising a transparent lateral surface, a first end surface, and a second end surface; a first lens positioned substantially perpendicular to and concentric with the axis of the axisymmetric form to the side of the first end surface; a second lens positioned substantially perpendicular to and concentric with the axis of the axisymmetric form on the side of the second end surface; and an image acquiring device positioned substantially coaxially with the second lens and beyond the second lens with respect to the second end surface.
PCT Publication WO 03/026272 to Gal et al., which is incorporated herein by reference, describes an imaging assembly comprising a first, essentially symmetric reflective surface, having a shape suitable to reflect a substantially panoramic view of an area surrounding it, and a second reflective surface, which is asymmetric with respect to said first reflective surface, i.e., which is positioned, with respect to the axis of symmetry of said first reflective surface, such that its movement in one or more directions reflects different portions of the area reflected by said first reflective surface, and the optical properties of said second reflective surface are such that area imaged by it is magnified with respect to the same portion of the area imaged by the first reflective surface.
PCT Publication WO 02/075348 to Gal et al., which is incorporated herein by reference, describes a method for determining azimuth and elevation angles of a radiation source or other physical objects located anywhere within an cylindrical field of view. The method uses an omni-directional imaging system including reflective surfaces, an image sensor, and an optional optical filter for filtration of the desired wavelengths. Use of two such systems separated by a known distance, each providing a different reading of azimuth and elevation angle of the same object, enables classic triangulation for determination of the actual location of the object.
PCT Publication WO 03/046830 to Gal et al., which is incorporated herein by reference, describes a self-contained omnidirectional imaging device. The device contains within it all mechanic, electronic, optic and electro-optic components required for its operation, namely: omnidirectional optics, image capture device, power source, illumination sources, transmitters, receivers, and additional optional elements for enhanced capabilities. In an embodiment, the device is housed inside a spherical structure, designed for deployment to potentially hazardous environments, in order to enable omnidirectional viewing of such environments without endangering the viewer.
PCT Publication WO 04/042428 to Gal et al., which is incorporated herein by reference, describes an omni-directional imaging assembly, which comprises a solid omni-directional lens comprising a vertical axis of symmetry; an upper surface, at least part of which is capable of reflecting rays that arrive from the inner side of the omni-directional lens; a transparent perimeter surface; a lower convex surface, at least part of which is capable of reflecting rays that arrive from the direction of the perimeter surface; and a transparent circular surface maintained in the lower convex surface around the vertical axis of symmetry. The light rays from a first 360 degree, panoramic, scene are refracted by the transparent perimeter surface, are then reflected by the lower convex surface towards the upper surface, and are then reflected by the upper surface towards the transparent circular surface, where they are refracted and exit the omni-directional lens. For some applications, the imaging assembly is combined with an illumination source to simultaneously provide both omni-directional imaging and omni-directional illumination. Also described are embodiments that comprise image capturing devices, embodiments that enable simultaneous imaging of the first scene and a second scene, and embodiments that are adapted to the requirements of endoscopic imaging.
PCT Publication WO 03/096078 to Gal, which is incorporated herein by reference, describes electro-optical assemblies, which are capable of capturing a full or nearly full spherical field of view.
PCT Publication WO 03/054625 to Gal et al., which is incorporated herein by reference, describes apparatus for panoramic stereoscopic imaging, comprising a first panoramic imaging assembly located at a first location, and a second panoramic imaging assembly located at a second location. The locations are located on a platform, which is a common horizontal plane.
PCT Publication WO 04/008185 to Gal et al., which is incorporated herein by reference, describes a wide-angle imaging assembly which comprises a main lens produced from an aspheric optical block. The aspheric optical block comprises a vertical axis of symmetry; a transparent upper surface, at least part of which is capable of reflecting rays that impinge upon it from the interior of the optical block; a transparent perimeter surface; and a transparent lower surface. The optical block is fabricated from material selected to enable optical transmittance of a specific spectral range. Light rays in the specific spectral range originating in a first scene, having a 360 degree panoramic perimeter, are refracted by the transparent perimeter surface, enter the optical block, are then reflected by the upper surface towards the transparent lower surface, where they are then refracted by the transparent lower surface, and exit through it.
Japanese Patent Application Publication JP 61-267725 A2 to Miyazaki Atsushi, which is incorporated herein by reference, describes an endoscope fitted with a conical surface-like mirror for observing both the side and the front of a pipe.
Japanese Patent Application Publication JP 71-91269 A2 to Yamamoto Katsuro et al., which is incorporated herein by reference, describes an endoscope having an irradiation port at a tip of a light guide. The port directly illuminates an observed surface, and the image of the observed surface is projected and reflected on a conical mirror.